|The AMIGA sample of isolated galaxies. II. Morphological refinement|
We present a refinement of the optical morphologies for galaxies in theCatalog of Isolated Galaxies that forms the basis of the AMIGA (Analysisof the interstellar Medium of Isolated GAlaxies) project. Uniformreclassification using the digitized POSS II data benefited from thehigh resolution and dynamic range of that sky survey. Comparison withindependent classifications made for an SDSS overlap sample of more than200 galaxies confirms the reliability of the early vs. late-typediscrimination and the accuracy of spiral subtypes within Δ T =1-2. CCD images taken at the Observatorio de Sierra Nevada were alsoused to solve ambiguities in early versus late-type classifications. Aconsiderable number of galaxies in the catalog (n = 193) are flagged forthe presence of nearby companions or signs of distortion likely due tointeraction. This most isolated sample of galaxies in the local Universeis dominated by two populations: 1) 82% are spirals (Sa-Sd) with thebulk being luminous systems with small bulges (63% between types Sb-Sc)and 2) a significant population of early-type E-S0 galaxies (14%). Mostof the types later than Sd are low luminosity galaxies concentrated inthe local supercluster where isolation is difficult to evaluate. Thelate-type spiral majority of the sample spans a luminosity rangeMB-corr = -18 to -22 mag. Few of the E/S0 population are moreluminous than -21.0 marking the absence of the often-sought superL* merger (e.g. fossil elliptical) population. The rarity ofhigh luminosity systems results in a fainter derived M* forthis population compared to the spiral optical luminosity function(OLF). The E-S0 population is from 0.2 to 0.6 mag fainter depending onhow the sample is defined. This marks the AMIGA sample as unique amongsamples that compare early and late-type OLFs separately. In othersamples, which always involve galaxies in higher density environments,M^*_E/S0 is almost always 0.3-0.5 mag brighter than M^*_S, presumablyreflecting a stronger correlation between M* andenvironmental density for early-type galaxies.
|Revised positions for CIG galaxies|
We present revised positions for the 1051 galaxies belonging to theKarachentseva Catalog of Isolated Galaxies (CIG). New positions werecalculated by applying SExtractor to the Digitized Sky Survey CIG fieldswith a spatial resolution of 1 arcsper 2. We visually checked theresults and for 118 galaxies had to recompute the assigned positions dueto complex morphologies (e.g. distorted isophotes, undefined nuclei,knotty galaxies) or the presence of bright stars. We found differencesbetween older and newer positions of up to 38 arcsec with a mean valueof 2 arcsper 96 relative to SIMBAD and up to 38 arcsec and 2 arcsper 42respectively relative to UZC. Based on star positions from the APMcatalog we determined that the DSS astrometry of five CIG fields has amean offset in (alpha , delta ) of (-0 arcsper 90, 0 arcsper 93) with adispersion of 0 arcsper 4. These results have been confirmed using the2MASS All-Sky Catalog of Point Sources. The intrinsic errors of ourmethod combined with the astrometric ones are of the order of 0 arcsper5.Full Table 1 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/411/391
|The first seven UK supernova discoveries|
This paper outlines the early history of amateur patrolling forsupernovae from the United Kingdom, describes the methods employed bythe patrollers, and provides a detailed description in the words of theobservers of the first seven successful discoveries, made between 1996October and 1998 April.
|The UK Nova/Supernova Patrol-The First 25 Years|
The history, accomplishments, and activities of the UK Nova/SupernovaPatrol are described.
|Supernova 1999eg in IC 1861|
IAUC 7280 available at Central Bureau for Astronomical Telegrams.
|Supernova 1999eg in IC 1861|
IAUC 7275 available at Central Bureau for Astronomical Telegrams.
|Arcsecond Positions of UGC Galaxies|
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
|Neutral Hydrogen Around Early-Type Galaxies|
When early-type (E,S0) galaxies have neutral hydrogen gas associatedwith them, it is often located over a very extended region. Thissuggests several possible origins for the gas, either intrinsic to thegalaxy or from an external source. We present 21 cm H I maps aroundearly-type galaxies to study the distribution of gas in the galaxiesvicinity and address these possibilities. We examine two sets ofobjects: (I) early- type galaxies with conflicting HI measurements thatmight indicate unusual gas distributions, and (2) galaxy groups that aredominated by early-type galaxies. We have identified several galaxieswith extended H I disks, and a number of H I companions that may beinteracting with the early-type galaxies and may be confusing H Iobservations. Many of the companions can be optically associated withuncataloged dwarf galaxies, but a few are quite peculiar or have noclear optical association. We discuss the implications of these resultsfor the origin of H I in early-type galaxies.
|Nearby galaxy flows modeled by the light distribution - Distances, model, and the local velocity anomaly|
Tables giving measured galaxy distances used to construct a map ofobserved peculiar velocities, and giving a grid of the distribution oflight used to construct a map of expected peculiar velocities arepresented. A preferred model was developed which yielded a best fitbetween these maps, and this model was used to generate output kinematicdistances which are recorded for groups and individual galaxies withV0 of less than 3000 km/s. In terms of the ratio ofpeculiar-to-systemic velocities, the local velocity anomaly is the mostimportant perturbation involving substantial numbers of galaxies forthis case. The ratio of these quantities in this case is larger than forthe more famous cases of the Virgocentric or Great Attractorperturbations. Maps which illustrate the fit of the present mass modelto the velocity data in the local region are provided. A graphicaldemonstration of the relative importance of large-scale streaming tolocal motions within the context of this model is presented.
|Uncertainties in 21 centimeter redshifts. I - Data|
High-precision data on the 21-cm redshifts, profile widths, and shapesfor 625 galaxies are presented. Each galaxy is listed in across-identification and morphology table. High-resolution spectra arealso given for each galaxy. Internal redshift consistency is roughly 1km/s for galaxies for which the S/N is above 15. No systematic effectshave been found which might influence the observed redshift quantizationat 72.5 km/s or its submultiples.
|A 21 CM survey of the Pisces-Perseus supercluster. II - The declination zone +21.5 to +27.5 degrees|
Neutral-hydrogen 21-cm line spectra and derived parameters are presentedfor a sample of spiral galaxies in the region bounded by an R.A. greaterthan 22 h and less then 0.04 h, and a declination greater than +21 deg30 min and less than +27 deg 30 min, covering the Zwicky fields 470 to488, as the second installment of a survey of the region of thePisces-Perseus supercluster. New H I line observations made with theArecibo 305 m telescope detected 275 galaxies of 318 studied. Atabulation of derived galaxian properties is given. The redshiftdistribution shows gross departures from that expected for a sample withsimilar magnitude characteristics but homogeneously located in space.These new data will be incorporated into the overall survey of thethree-dimensional structure in the Pisces-Perseus region.
|Radio emission in isolated and cluster spiral galaxies|
In the 2380-MHz continuum radio observations presented for two samplesof spiral galaxies observed with the NAIC Arecibo 305-m telescope, thesamples have been chosen in such a way that they differ markedly in thedensity of surrounding galaxies. One sample includes exclusivelygalaxies from the Karachentseva (1973) Catalog of Isolated Galaxies, theother only galaxies found within one Abell radius from the center ofnearby Abell clusters. The goal is to obtain a comparison of the radioproperties of the galaxies in these two samples, to ascertain whetherenvironmental processes affect significantly their radio emissivity.Above a threshold of five times the rms confusion, 7 percent of thecluster galaxies and 5 percent of the isolated ones are detected. Withthe caution required by the effects of confusion on the single-dishobservations, no significant differences are found in theradio-continuum properties of these two samples.
|Neutral hydrogen in isolated galaxies. IV - Results for the Arecibo sample|
A standard sample for the comparison of the H I content of galaxies invarious intergalactic environments is presently defined by means ofobservations of 324 isolated galaxies lying in the declination rangeaccessible to the Arecibo 305-m telescope. Both mapping and single pointspectra are used to compute the integral properties of these galaxies.Neutral hydrogen was detected in 288 of the 324 galaxies surveyed, andit is noted that the optical diameter of a spiral disk is bettercorrelated with the hydrogen mass than the morphological type. When usedto define a measure of H I content, the isolated galaxy sample canpredict 'normalcy' with an accuracy that carries a standard error ofabout 0.20 in the log of the H I mass, if a dependence on disk size, aswell as type, is taken into account.
|Neutral hydrogen in isolated galaxies. II - The large angular diameter galaxies|
Fifty-two of the large-angular-diameter (greater than or equal to 2.5arcmin) galaxies included in the 21-cm survey of isolated galaxies beingundertaken at Arecibo are mapped along their optical major axes usingthe 305-m telescope and the low sidelobe flat feed system. The observedfluxes are then compared with a numerical convolution of an assumed H Idistribution and the beam pattern to produce an estimate of thecharacteristic size. The derived H I scale length is that radiusinterior to which 70% of the model's H I mass is contained. With stillan appreciable scatter, the H I diameter is on the average about 1.2times the UGC blue diameter (1), and exhibits no dependence onmorphological type for types later than Sa. Applying the observedrelationship between H I size and optical diameter and an assumed doubleGaussian (centrally depressed) H I surface density distribution givesproper corrections for source-to-beam size.
|Neutral hydrogen in isolated galaxies - First results for five early-type systems|
The neutral hydrogen properties of the first five early-type galaxiesobserved in a survey of isolated galaxies are presented. The galaxiesare found in regions of very low density and hence are 'isolated' atleast with respect to the majority of galaxies. Among this sample,early-type systems are extremely rare. The five isolated early-typegalaxies presented here contain substantial masses of neutral hydrogen.In addition, their hydrogen-mass-to-luminosity ratios vary substantiallybut are high relative to published values for other early-type galaxies.The morphological classification of these galaxies is uncertain, but, inlight of the remainder of the sample, their distinctiveness isestablished.